UI: Ignore wheelEvent for properties

Ignore wheelEvent using subclass
slider,spinbox,combobox with eventhandlers:
wheelEvent - ignore if widget is not focused,
leaveEvent - clear focus when mouse leaves event.

Use these new subclass widgets in properties
to ignore wheelEvent when scrolling.

UI/slider-ignorewheel.cpp

@@ -0,0 +1,19 @@
+#include "slider-ignorewheel.hpp"
+
+SliderIgnoreScroll::SliderIgnoreScroll(QWidget *parent) : QSlider(parent)
+{
+	setFocusPolicy(Qt::StrongFocus);
+}
+
+void SliderIgnoreScroll::wheelEvent(QWheelEvent * event)
+{
+	if (!hasFocus())
+		event->ignore();
+	else
+		QSlider::wheelEvent(event);
+}
+
+void SliderIgnoreScroll::leaveEvent(QEvent * event)
+{
+	clearFocus();
+}